PCRE... and i thought i understood it

[silentace]

Ok so here are a few examples of what i am trying to allow

2E2X1
3C051
5B174

First spot needs to be a number, second a letter, third a number again, forth any of the following: X,1,3,5,7,9 and then fifth a number again.

I am also trying to allow it to have "DEP" and "Civ" as an option to type as well but would like the capitalization to hold. So here is my expression but i don't fully understand it as much as i thought i did

^[0-9][A-Z][0-9][X13579][0-9]|[DEP]|[Civ]$

Any help would be much appreciated.